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. Bone
Chest Wall Anatomy * Skin, subcutaneous fat * Blood vessels, lymphatics, nerves * Bone, cartilage * Muscles * Endothoracic fascia, fibroelastic connective tissue between inner aspect of chest wall and costal pleura FUNCTION * Musculoskeletal cage: Surrounds cardiorespiratory system; effects respiration by expanding and contracting during ventilation SURFACE LANDMARKS * Suprasternal (jugular) notch: At superior manubrium of sternum; between sternal ends of clavicles * Sternal angle: Landmark for internal thoracic anatomy;anterior projection at level of costal cartilage of 2nd rib * Costal margin: Inferior margins of lowest ribs and costal cartilages SKELETAL STRUCTURE * Thoracic Vertebrae ** Twelve vertebrae (T1-T12) * Shoulder Girdle ** Clavicle, scapula and proximal humerus * Sternum ** Flat, broad bone forms anterior thoracic wall; three parts (manubrium, body, xiphoid process) * Scapula ** Large, triangular flat bone; parallel to upper posterior thorax; extends from 2nd-7th ribs bilaterally ** Glenoid fossa at glenohumeral joint * Ribs ** 12 pairs, symmetrically arrayed; numbered in accordance with attached vertebral body MUSCLES * Pectoral ** Pectoralis major ** Pectoralis minor * Intercostal ** External ** Internal ** Innermost * Serratus Anterior * Back Muscles ** Superficial extrinsic muscles: trapezius, latissimus dorsi, levator scapulae, rhomboids ** Intermediate extrinsic muscles (superficial respiratory muscles): serratus posterior ** Deep intrinsic muscles: splenius muscle, erector spinae muscles, deep transversospinales muscles VESSELS * Arteries ** Internal thoracic (internal mammary): Branch of subclavian artery; descends posterior to first six costal cartilages; supplies upper anterior chest wall *** Supplies anterior intercostal arteries to first six intercostal spaces * Veins ** Azygos vein receives drainage from posterior intercostal veins, hemi-azygos and accessory hemi-azygos veins * Lymphatics ** Chest wall drainage through thoracic duct (right upper limb, right face and neck drained by right lymphatic duct) NERVE: * Anterior rami of thoracic spinal nerves (T1-T11) supply skin, tissues of chest wall; form intercostal nerves * Intercostal nerves run in costal groove, between internal and innermost intercostal muscles * Brachial plexus: Branching network of nerve roots, trunks, divisions, cords and branches ** Spinal roots form three trunks; behind clavicle, each dividing into anterior and posterior divisions ANATOMIC REGIONS * Thoracic Inlet ** Opening at superior end of thoracic rib cage; conduit for cervical structures to enter thorax ** Bounded by T1 vertebral body, right and left 1st ribs and their costal cartilages, and manubrium of sternum * Thoracic Outlet ** Opening at inferior end of thoracic rib cage; conduit for thoracic structures to exit thorax ** Bounded by T12 vertebral body, right and left 12th ribs, costal cartilages of 7th-12th ribs, xiphisternal joint * Breast and Pectoral Region ** Anterior and superior part of chest; muscles and fascia assist movement of upper limb; mammary glands Congenital and Developmental Abnormalities * Pectus excavatum (syn. funnel chest): Abnormal growth of costal cartilages; sternal depression/rotation; compression/obscuration of right heart border on PA radiograph * Pectus carinatum (syn. pigeon breast): Abnormal growth of costal cartilage; sternal protrusion * Cervical rib: Supernumerary rib, usually arising from seventh cervical vertebra * Poland syndrome: Uncommon; partial or total absence of pectoralis major muscle; associated malformations of ipsilateral ribs (2-5) and clavicle; congenital absence of ipsilateral breast tissue